It is a surgical axiom that wound tension should be avoided at all costs. In surgical procedures a certain amount of skin may be excised and easily closed but there is a point beyond which closure results in wound tension or the wound cannot be closed resulting in a deficit of skin. Skin tension is of particular importance in wound healing because a highly stressed wound environment delays wound healing. A wound sutured closed under tension will result in maximum scarring. Wound tension is also one of the factors for initiation of a keloid or hypertropic scar. For the plastic surgeon the qualitative end result is one of the most crucial factors in reconstructive surgery. The attention to minute details can be the difference between success and failure for plastic surgical procedures where cosmetic appearance is a critical factor. Tension free skin is especially important in facial areas or when skin coverage is required to cover a prosthesis. Wounds closed under tension can create distortions of nearby facial features such as eyelids, lips, etc., create wide displeasing scars or result in exposure of an implantable prosthesis.
The physician has three surgical means to obtain additional tension free skin namely: (A) skin grafts, (B) free flaps and (C) internally placed tissue expansion devices.
A. Skin grafts involve the transfer from a donor site, the epidermis and a measured portion of the dermis to a recipient site formed as a shallow well-vascularized wound. The donor site will take as long as three weeks to heal. Skin grafts provide superficial coverage and do not replace deeper tissue layers such as subcutaneous tissue. With skin grafts there is no satisfactory match in color, texture or thickness to harmonize with surrounding tissue.
B. Tissue flaps are used in the procedures that involve the transfer of skin and underlying structures such as subcutaneous tissue, fascia and muscle to fill a defect. This procedure involves detachment of the tissue from its original site, transfer of the flap to the defect, and suture of the flap over the defect. In a free flap the flap tissue is completely removed from the donor site and reattached to the wound using microvascular techniques. In all other flap procedures there is a base which remains attached and supplies circulatory support for the flap.
C. Present internal tissue expansion devices have at least three disadvantages: (1) they involve multi-staged surgical operations, (2) they sacrifice the well being of the donor site for the need of the recipient site, (3) and the time between first and second surgical procedure can be as long as one to four months. Present internal tissue expanders are essentially inflatable balloons or pouches that are surgically placed into and under subcutaneous tissue in an area close to the defect to be corrected. After a time period for the surgical incision to heal, pressure and volume of the pouch/balloon is incrementally increased by injections of saline into the pouch/balloon. With this technique excessive stresses are placed on the skin due to the high forces exerted by the internal tissue expander. The typical method of determining expansion pressure is measured by pain response from the patient. While these stresses are initially high, the force levels dissipate as the skin stretches necessitating cyclic injections of saline into the pouch/balloon over weekly time periods to create additional new skin. When a sufficient amount of skin is created the pouch/balloon is removed, and the new skin is incised and the donor site closed by suture. This new skin is sutured to cover the defect which results in a tension free closure of the wound. Tissue expansion with internally placed tissue expanders has a 38% complication rate. Incisional dehiscence and exposure of the internal expander is a major complication of internally placed tissue expanders. Other complications such as leakage of fluid, necrosis of skin, hematoma and spontaneous deflation of the expander may cause abandonment of the procedure. The frequency of saline precutaneous injections of sterile saline predispose the implant cavity to infection which is serious and involves removal of the internal expander. The internally placed expander is a foreign body, and particles from the expander which delaminate or flake from the surface into the implant cavity and tissue cause an inflammatory reaction.